On Feb 12, 2026, at 1:33 PM, Bill Gee wrote: > > Hi Charles - > > The APC units I have are dumb-serial. Back-UPS 500, Back-UPS-600 and > Back-UPS-650. They use serial cable 940-0020B. They are listed in apcupsd > as "Dumb UPS". The sticker on the back says "Model BK650MC". > > Reading through the docs you linked, I cannot tell for sure if these are > supported.
Heh, I was making it too complicated. "Dumb UPS" translates to "contact-closure" or "generic UPS" in NUT parlance. (I was concerned it was one of the early Smart serial protocol devices.) https://networkupstools.org/stable-hcl.html?model=Back-UPS lists Cable 940-0020B, and includes the necessary configuration option for the genericups driver (upstype=2). Here's the full genericups documentation: https://networkupstools.org/docs/man/genericups.html > Here is a sample output from apcupsd: > ======================= > Date Range: yesterday > APC : 001,018,0458 > DATE : 2026-02-07 07:46:29 -0600 > HOSTNAME : zoneminder2 > VERSION : 3.14.14 (31 May 2016) redhat > UPSNAME : zoneminder2 > CABLE : APC Cable 940-0020B > DRIVER : DUMB UPS Driver ... As you're probably aware, the contact-closure interface is just a bunch of modem control signals repurposed for AC/battery and battery good/low. For instance, MBATTCHG and MINTIMEL seem like they can only be compared against battery charge and time-left values that a smart UPS would provide, so I would guess that they are not currently working in apcupsd? Given some of the uncertainty with the proprietary cables, you may want to schedule some downtime to test with a computer running a live CD, or some other system that can survive a bad shutdown without trashing important data. Monitoring should be straightforward, but the shutdown signal to the UPS (and getting NUT and the OS to play nicely around when that signal is sent) is what would give me pause. Hope that helps, - Charles _______________________________________________ Nut-upsuser mailing list [email protected] https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/nut-upsuser
